The present invention relates to electrostatic treatment of fluid systems and more particularly to the construction and operation treating devices having electrostatic fields.
Apparatus for the treatment of moving liquid by causing electric current flow or discharge therein and/or impressing electrically induced fields thereacross have been known for many years, but the application of such devices to common industrial and domestic problems, such as water system scaling and clogging, has met with varying success. Some installations have appeared to be functional while others which seemed to be operating under generally similar circumstances obviously failed and no broadly accepted reasons for the different results have been advanced. The optimum type, size and characteristics of a treater to produce desired and reliable results in a particular environment appear to have been unnecessarily limited with respect to DC voltage imposed on the electrostatic field. A predictive method is disclosed in U.S. Pat. No. 4,073,712 wherein a positively charged axially placed conduit electrode insulated by a dielectric material provides an electrostatic field through flowing water in the conduit whereabout the conduit has a negatively charged electrode, thereby providing a three capacitor system.
A large number of factors and complex interactions are apparently involved in the treating process. This seems logical since such liquid systems are themselves usually highly complex, including variations in dissolved salts, suspended solids, turbulence, pH, piping, electrical environment, temperature, pressure, etc. Many liquid clogging mechanisms, including water system scaling, involve the electrostatic relations between suspended particles, the carrier liquid and the walls of the piping network. Thus, an electrostatic field effectively developed across a section of flowing water primarily affects not only the water, but mainly suspended, especially colloidal size, particles immersed in the water. The effect of the field will depend, in large measure, upon the relationship of the natural electrostatic charge on such immersed particles to the electrostatic charge on the various surfaces of the treater and how the latter charge induces a response on the liquid contacting surfaces of the piping network. If relative conditions are proper, the particles will be urged by the field to remain in suspension or migrate toward a charged electrode isolated from the walls of the piping network, thus reducing the tendency to form flow restricting deposits. The reduction of colloid particles which are capable of acting as seeds for nucleation of scale building crystal formations results in reduced tendency for scale deposition.
The natural electrostatic charge on the immersed particles in the liquid, or more accurately, the overall charge effect of the various groups of particles normally associated in the same system, can be determined by known procedures, but the control of the electrostatic charge on critical treater surfaces has been heretofore very limited due to configuration of the electrodes. The present invention reverses a decades old method of fabricating conduit electrostatic field treatment devices such that the positive, ground electrode is situated generally within the axial space of the conduit, whereabout are situated dielectric insulated negatively charged electrode(s) such that the liquid flowing in the conduit becomes negatively charged for later process advantage.
The electrostatic field between particular water treater surfaces, in large part, can be predicted and controlled by limiting certain parameters in treater construction and installation, especially the dielectric constant of the insulating material or materials in contact with the water, the efficiency of the insulating material or materials and seals in preventing charge leakage, and the physical size ratio of the treater parts which form the surfaces producing the electrostatic field across the water complex under treatment. The word "water", as used herein, means water complexes containing dissolved and suspended solids, etc., as are normally found in a great many industrial and domestic applications. Of more importance, however, is to provide a method whereby high DC voltages may be effectively developed across the flowing fluids.
The manipulation of electrical potentials, to produce relationships within certain parameters calculated from an equation which presents a mathematical model of the treater as three capacitors connected in series, results in operable treaters, while devices having relationships falling outside those parameters are apparently less-functional or only marginal in operation. The parameters of those variables are described with reference to a specific example below.
The principal objects of the present invention are: to provide operable and efficient electrostatic water treaters; to provide such treaters which function to predictably inhibit the formation of scale from colloidal particles immersed in flowing water; to provide a treater construction which substantially reduces the formation of scale in piping systems and may function to remove scale already formed; to provide a method of designing operable and efficient electrostatic treaters for particular installations; to provide a method of treating water to reliably inhibit the formation of certain clogging deposits in the piping system containing same; to provide a dependable alternative to many types of chemical water treatment; and to provide such methods and apparatus which have wide application in improving desired properties of water for industrial and domestic purposes at minimal cost and maximum safety.
In specific examples of the invention, DC voltage is applied across the electrodes at a range unexpectedly high in relation to the teaching of the prior art in this field. The placement of sufficient axially facing positively charged electrode surface area or a plurality of separate electrodes and surfaces about an axial space-occupying negative ground electrode dramatically increase the surface area in which negative charge may be extended into the flowing liquid, thereby permitting comparatively extremely high DC voltages.
The present invention comprises an insertion type electrode adapted to operate at modulated high voltages by use of a thin layer polymer as a dielectric.